Method and device for resource allocation and release in wireless sidelink communication

ABSTRACT

This disclosure relates to methods and devices for wireless sidelink resource allocation for a user equipment (UE) assisted by an anchor UE. Various mechanisms are disclosed for handling releasing of the anchor UE initiated by either the anchor UE or the assisted UE, and for handling sidelink resources already allocated to the UE by the anchor UE prior to the release. Additional mechanisms are disclosed for using an anchor UE to assist in allocating sidelink resources to multiple UEs configurable in a shared manner or non-shared manner.

CROSS REFERENCE

This application is a continuation of and claims priority toInternational Patent Application No. PCT/CN2020/083906, filed Apr. 9,2020, which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure is directed generally to wireless communications andparticularly to sidelink communication resource allocation,configuration, and release.

BACKGROUND

User equipments in a wireless network may communicate data with oneanother via direct sidelink communication channels without the databeing relayed by any wireless access network nodes. In some applicationscenarios of sidelink communications such as those involving vehicularwireless network devices, communication resource allocation andconfiguration for one communication terminal may involve anothercommunication terminal in addition to a base station. It is critical toprovide a resource allocation, provisioning, and release mechanism toenable low-power and efficient use of sidelink communication resources.

SUMMARY

This disclosure is directed to methods, systems, and devices related towireless communication, and more specifically, to resource allocation,configuration, and release in sidelink communication betweencommunication terminals.

In one embodiment, a method for releasing resource allocation assistancein wireless sidelink communication by a first user equipment (UE) isdisclosed. The method may include determining, after an associationbetween the first UE and a second UE is established for the second UE toassist the first UE in sidelink resource allocation, a releaseindication indicating that the first UE no longer needs the second UE toassist in the sidelink resource allocation; and transmitting, upon thedetermination of the release indication, a release information to thesecond UE for indicating to the second UE that the first UE no longerneed the second UE to assist in the sidelink resource allocation or thata mode for the sidelink resource allocation for the first UE haschanged.

In another embodiment, another method for releasing resource allocationassistance in wireless sidelink communication by a first UE isdisclosed. The method may include determining, after an associationbetween the first UE and a second UE is established for the first UE toact as an anchor UE to assist the second UE in sidelink resourceallocation, a release indication indicating that the first UE is nolonger assisting the second UE in the sidelink resource allocation; andtransmitting a release information to the second UE for indicating tothe second UE that the first UE is no longer assisting the second UE inthe sidelink resource allocation

In another embodiment, a method for obtaining assistance in sidelinkcommunication resource allocation by a first UE from a second UE isdisclosed. The method may include transmitting a request for assistancein sidelink communication resource allocation to the second UE;receiving a sidelink communication resource allocation information sentby the second UE in response to receiving the request; and selectingfrom allocated resources indicated by the sidelink communicationresource allocation information.

In another embodiment, a method for assisting a second UE in wirelesssidelink resource allocation by a first UE is disclosed. The method mayinclude transmitting, by the first UE, a sidelink message indicating thefirst user equipment can assist another user equipment in sidelinkresource allocation; receiving, by the first UE, the sidelink assistancerequest message; and transmitting, by the first UE, a response to thereceived sidelink assistance request message to the second UE toindicate that the first UE can assist the second UE in sidelink resourceallocation. The sidelink message may include at least one of a mode ofresource allocation for the second UE comprising at least one of a modefor resource schedule by a serving cell, a mode for resource allocationby UE autonomous selection, a semi-persistent resourceallocation/scheduling mode, a dynamic resource allocation/schedulingmode, a mode for multi-shot resource allocation mode, or single shotresource allocation mode; an indication of a radio access technology(RAT) of the first UE; or a PC5 RAT supported by the first UE.

In another embodiment, a method for wireless sidelink resourceallocation for a first UE is disclosed. The method may includereceiving, by the first UE, a sidelink configuration message indicatinga plurality of modes of sidelink resource allocation that can besimultaneously used by the first UE; and obtaining a sidelink resourceallocation, by the first UE, via two or more of the plurality of modesof sidelink resource allocation. The plurality of modes of sidelinkresource allocation may include two or more of a mode for resourceallocation by a serving cell, a mode for resource allocation by UEautonomous resource selection, or a mode for resource allocation viaassistance from a second UE

Various devices are further disclosed. Each of these devices includes aprocessor and a memory, wherein the processor is configured to readcomputer code from the memory to implement any one of the methods above.

Computer-readable media are further disclosed. Each of thecomputer-readable media includes instructions which, when executed by acomputer, cause the computer to carry out any one of the methods above.

The above and other aspects and their implementations are described ingreater detail in the drawings, the descriptions, and the claims below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example diagram of a wireless communicationnetwork in accordance with various embodiments.

FIG. 2 illustrates an example logic follow for an anchor UE to assistanother UE in sidelink resource allocation.

FIG. 3 illustrates an example logic follow for configuring, restarting,and deactivating a timer used in a procedure for releasing an anchor UEfrom assisting a second UE in sidelink resource allocation.

FIG. 4 illustrates an example logic flow for releasing an anchor UE fromassisting a second UE in sidelink resource allocation as initiated bythe anchor UE.

FIG. 5 illustrates an example logic flow for releasing an anchor UE fromassisting a second UE in sidelink resource allocation as initiated bythe anchor UE.

FIG. 6 illustrates an example logic flow for a UE to switch its anchorUE in assisting in sidelink resource allocation.

FIG. 7 illustrates another example logic flow for an anchor UE to assista second UE in sidelink resource allocation.

DETAILED DESCRIPTION

The technology and examples of implementations and/or embodiments inthis disclosure can be used to improve performance in wirelesscommunication systems. The term “exemplary” is used to mean “an exampleof” and unless otherwise stated, does not imply an ideal or preferredexample, implementation, or embodiment. Section headers are used in thepresent disclosure to facilitate understanding and do not limit thedisclosed technology in the sections only to the corresponding section.Please note that the implementations may, however, be embodied in avariety of different forms and, therefore, the scope of this disclosureor claimed subject matter is intended to be construed as not beinglimited to any of the embodiments set forth below. The variousimplementations may be embodied as methods, devices, components, orsystems. Accordingly, embodiments of this disclosure may, for example,take the form of hardware, software, firmware or any combinationthereof.

A vehicle network refers to a network system for wireless communicationand information exchange among vehicles, pedestrians, roadsideequipments, and the Internet and other data networks in accordance withvarious communication protocols and data exchange standards. Vehiclenetwork communication helps improve road safety, enhance trafficefficiency, and provide broadband mobile data access and inter-networknode data exchanges. The vehicle network communication may becategorized into various types as differentiated according to thecommunication endpoints, including but not limited to vehicle-to-vehicle(V2V) communication, vehicle-to-infrastructure/vehicle-to-network(V2I/V2N) communication, and vehicle-to-pedestrian (V2P) communication.These types of communication are referred to, collectively, asvehicle-to-everything (V2X) communication.

Such a vehicle network may heavily rely on sidelink communicationbetween the terminal devices or user equipments (UEs) in the network.Sidelink communication, as used in this disclosure, refers to a directwireless information exchange between UEs. For example, V2Xcommunication may rely on direct sidelink data exchange from a source UEto a destination UE via an air interface without forwarding by anywireless base station. Such mode of communication has been researchedand implemented in the 3rd Generation Partnership Project (3GPP). Anexample V2X subsystem based on sidelink communication technology isillustrated as part of FIG. 1 and may be referred to as, for example,PC5-based V2X communication or V2X sidelink communication.

The application scenarios for V2X communication has increasinglyexpanded and diversified. Advanced V2X services and applications includebut are not limited to vehicle platooning, extended sensors,semi-autonomous driving, fully autonomous driving, and remote driving.These applications and services require increasingly higher networkperformance including broader bandwidth, lower latency, and higherreliability. For example, these applications and services may requirethat the underlying sidelink communication technology supportcommunication data packets of 50 to 12000 bytes in size, messagetransmission rates of 2 to 50 messages per second, maximum end-to-enddelays of 3 to 500 milliseconds, transmission reliability of 90% to99.999%, data transmission rates of 0.5 to 1000 Mbps, and signal rangesof 50 to 1000 meters, depending on specific data services needed forthese applications.

While being capable of communicating among themselves using sidelinks,the various UEs described above may also be connected to wireless accessnetworks, and to a core network via the access networks. The wirelessaccess network and core network may be involved in configuring andprovisioning communication resources needed for data and controlinformation transmission/reception for sidelink communication. Anexample wireless access network may be based on, for example, cellular4G LTE or 5G NR technologies and/or formats. FIG. 1 shows an examplesystem diagram of a wireless access communication network 100 includingUEs 102, 124, and 126 as well as a wireless access network node (WANN)104. Each of the UEs 102, 124, and 126 may include but is not limited toa mobile phone, a smartphone, a tablet, a laptop computer, a vehicleon-board communication equipment, a roadside communication equipment, asensor device, a smart appliance (such as a television, a refrigerator,and an oven), or other devices that are capable of communicatingwirelessly over a network. The UEs may indirectly communicate with eachother via the WANN 104 or directly via sidelinks. As shown in FIG. 1 ,each of the UEs such as UE 102 may include transceiver circuitry 106coupled to an antenna 108 to effectuate wireless communication with theWANN 104 or with another UE such as UE 124 or 126. The transceivercircuitry 106 may also be coupled to a processor 110, which may also becoupled to a memory 112 or other storage devices. The memory 112 maystore therein computer instructions or code which, when read andexecuted by the processor 110, cause the processor 110 to implementvarious ones of the methods for sidelink resourceallocation/configuration/release and data transmission/receptiondescribed herein.

Similarly, the WANN 104 may include a base station or other wirelessnetwork access points capable of communicating wirelessly over a networkwith one or more UEs and communicating with a core network. For example,the WANN 104 may be implemented in the form of a 4G LTE base station, a5G NR base station, a 5G central-unit base station, or a 5Gdistributed-unit base station. Each type of these WANNs may beconfigured to perform a corresponding set of wireless network functions.The WANN 104 may include transceiver circuitry 114 coupled to an antenna116, which may include an antenna tower 118 in various forms, toeffectuate wireless communications with the UEs 102, 124, and 126. Thetransceiver circuitry 114 may be coupled to one or more processors 120,which may further be coupled to a memory 122 or other storage devices.The memory 122 may store therein instructions or code that, when readand executed by the processor 120, cause the processor 120 to implementvarious functions. These functions, for example, may include thoserelated to the sidelink resource allocation, configuration, provisioningand releases described below.

For simplicity and clarity, only one WANN and three UEs are shown in thewireless communication access network 100. It will be appreciated thatone or more WANNs may exist in the wireless communication network, andeach WANN may serve one or more UEs. While the UEs 102, 124, and 126 ofFIG. 1 are shown as being served within one serving cell, they mayalternatively be served by different cells and/or by no cell. Whilevarious embodiments of sidelink communication below are discussed in thecontext of the particular example cellular wireless communication accessnetwork 100, the underlying principle apply to other types of wirelesscommunication networks.

Sidelink communication among the various UEs of FIG. 1 may supportco-existence of various distinct communication cast types includingunicast, group-cast (or multicast), and broadcast. In conventionaltechnologies, the UEs deployed in the access network 100 may be requiredto perform exhaustive monitoring of a large range of sidelink wirelessresources in either unicast, group-cast, or broadcast mode, therebyincurring a large power consumption. Such power consumption may be at anunacceptably high level for some low power UEs. To counter suchproblems, a low-power UE may request another UE to serve as an anchor UEto assist in allocating sidelink resources for the low-power UE. In sucha manner, the anchor UE that is less limited by power consumption maytake charge of monitoring and sensing the sidelink transmission resourcepools to provide assistance in sidelink resource allocation for thelow-power UE. Accordingly, the low power UE can reduce its frequency andamount of sensing and monitoring of the sidelink communication resourcepools. The term “anchor UE” is used in this disclosure to indicate anassistance role of the UE in resource allocation for other UEs.

While the various implementations below may benefit resource allocationand release for low-power UEs, the underlying principles apply tosidelink resource allocation and release for any other UEs.

The various embodiments described below relate to example procedures for(1) one UE to establish an assistance relationship with an anchor UE toobtain assistance in sidelink resource allocations, (2) release of suchassistance relationship under various conditions, and (3) selection ofconfigured sidelink resources allocated from the anchor UE by the UEbeing assisted.

First Embodiment (Procedure for Assisted Sidelink Resource Allocation byan Anchor UE)

As an example, this embodiment describes communication proceduresbetween the UE 102 and the UE 124 of FIG. 1 in order for the UE 102 toact as an anchor UE to assist in allocating sidelink resources for theUE 124 with reference to FIG. 2 . It is assumed that UE 102 qualifiesfor serving as an anchor UE. Example procedures for establishing UE 102as being qualified for serving as an anchor UE are described in PCTInternational Application No. PCT/CN2020/077568 filed with the ChinesePatent Office on Mar. 3, 2020 by the same Applicant as this currentpatent application and entitled “Device and Methods for AllocatingResources for Sidelink Transmission,” which is herein incorporated byreference in its entirety.

As shown in FIG. 2 , the anchor UE 102 may transmit a sidelink messageindicating that the UE 102 is serving as an anchor user equipment (202).The sidelink message may be carried in a sidelink broadcast message, asidelink group-cast message, a sidelink radio resource control (RRC)message, a PC5-MIB message, or a sidelink control information message.Accordingly, the sidelink message may be transmitted to the UE 124 inthe manner of broadcast, group-cast, or unicast.

In some implementations, the sidelink message may include, for example,access control information with respect to the UE 102. The accesscontrol information may include, for example, a channel quality betweenUE 102 and a cell serving the UE 102, a current load rate of the UE 102,a number of user equipments for which the UE 102 is assisting inallocating sidelink resources, a geographical location identification ofthe UE 102, and a quality of service supported by the UE 102.

Additionally or alternatively, the sidelink message may include, forexample, a mode of resource allocation for the UE 124. Such a model ofresource allocation may include but is not limited to a mode forresource allocation by a serving cell, a mode for resource allocation byUE autonomous selection, a semi-persistent resourceallocation/scheduling mode, a dynamic resource allocation/schedulingmode, a mode for multi-shot resource allocation mode; or single shotresource allocation mode.

Additionally or alternatively, the sidelink message may include anindication of a current a ratio access technology (RAT) of a current Uuinterface between the UE 102 and its serving cell, including but notlimited to E-UTRAN technology, new radio (RN) technology or double-linkconnection technology.

Alternatively or additionally, the sidelink message may include a PC5radio access technology supported by the UE 102.

Alternatively or additionally, the sidelink message may include, forexample, an indication that the UE 102 supports relay function or roadside unit function. The sidelink message may further include, forexample, destination identity indicating that the UE 102 is capable ofassisting in allocating sidelink resources for sidelink transmission ofthe UE 124 having such a destination identity, a quality of serviceinformation indicating that the UE 102 is capable of assisting inallocating sidelink resources for sidelink transmission of the UE 124with such a quality of service information, a transmission typeindicating that the UE 102 is capable of assisting in allocatingsidelink resources for sidelink transmission of the UE 124 of such atransmission type, a serving cell identifier indicating a cell servingthe UE 124, a number of allocable resources in a sidelink transmissionresource pool, a CBR of the transmission resource pool, and a resourceusage rate indicating a rate of allocated resources to allocableresources in the transmission resource pool.

As further shown by 204 of FIG. 2 , the UE 124 may receive the sidelinkmessage indicating that the UE 102 is serving as an anchor userequipment. Upon receiving the sidelink message, the UE 124 may transmitto a request message requesting for assisting in allocating sidelinkresources for the UE 124 to the UE 102 (206). The request message mayinclude, for example, an identifier of the UE 124, power savinginformation of the UE 124, sidelink destination index or destinationidentity to be used by the UE 124 in sidelink transmission, sidelinksource index or source identity to be used by the UE 124 in sidelinktransmission, sidelink quality of service information to be used by theUE 124 in sidelink transmission, coverage state information indicatingthat the UE 124 is in coverage or out of coverage of any wireless accessnetwork node, a serving cell identifier indicating a cell serving the UE124, a frequency information list to be used to be used by the UE 124 insidelink transmission, and a sidelink transmission type/cast type to beused by the UE 124 in sidelink transmission.

As shown in 208 of FIG. 2 , the UE 102 may receive the request messagefrom the UE 124. In response to the request message, the UE 102 maytransmit a response message indicating whether to assist in allocatingsidelink resources for the UE 124 to the UE 124 (210).

As further shown in 212 of FIG. 2 , the UE 124 may receive the responsemessage from the UE 102. The response message may indicate that the UE102 would assist in allocating sidelink resources for the UE 124. Such aresponse message may include, for example, the following information tofacilitate the UE 124 in obtaining sidelink resource allocation via theanchor UE 102:

-   -   scheduling request configuration set information, which        indicates the resource configuration for the UE 124 to transmit        scheduling request to the UE 102,    -   destination identity list, which indicates that the UE 102 is        capable of assisting in allocating sidelink resources for        sidelink transmission of the second user equipment with one or        more destination identities in the destination identity list,    -   a quality of service information, which indicates that the UE        102 is capable of assisting in allocating sidelink resources for        sidelink transmission of the UE 124 with the quality of service        information,    -   a transmission type or cast type, which indicates that the UE        102 is capable of assisting in allocating sidelink resources for        sidelink transmission of the UE 124 in such a transmission or        cast type, and    -   a range of HARQ process ID list indicating that the UE 102 is        capable of assisting in allocating sidelink resources for        sidelink transmission of the UE 124 with a HARQ process ID        within the range of HARQ process ID list.

Optionally, the response message may further include, for example,information on transmission resource pool for the UE 124.

Optionally, as indicated by 214 of FIG. 2 , where the response messageindicates that the UE 102 would assist in allocating sidelink resourcesfor the UE 124, the UE 102 may separately transmit the schedulingrequest configuration information to the UE 124. The scheduling requestconfiguration may be used by the UE 124 to construct a schedulingrequest.

As shown by 216 of FIG. 2 , the UE 124 may receive the schedulingrequest configuration information from the UE 102. Then, when the UE 124needs to perform a sidelink transmission, the UE 124 may generate ascheduling request for the sidelink transmission based on the receivedscheduling request configuration information, as shown in 218, andtransmit the scheduling request to the UE 102, as shown in 220.

In response to receiving the scheduling request as shown in 222, the UE102 may, for example, allocate sidelink resources in the transmissionresource pool for the UE 124 as shown in 224, and transmit the resourceallocation message including information of the allocated sidelinkresources to the UE 124, as shown in 226.

Alternatively, the UE 102 may transmit a buffer status reportconfiguration information to the UE 124 at 214. The UE 124 may thengenerate a buffer status report based on the buffer status reportconfiguration information (at 218) and transmit the buffer status reportto the UE 102 (at 220). In response to receiving the buffer statusreport, the UE 102 may for example, allocate sidelink resources in thetransmission resource pool of the UE 124 (224) and transmit the resourceallocation message including information of the allocated sidelinkresources to the UE 124 (226).

Optionally, prior to transmitting to the UE 102 the request messagerequesting for assisting in allocating sidelink resources for the UE 124(206), if the UE 124 is covered by a WANN such as the WANN 118, the UE124 may transmit a radio resource signaling (RRC) message to the WANN118. The RRC message may carry, for example, at least one of identifierof the UE 124, identifier of cell serving the UE 124, power savinginformation of the UE 124, sidelink destination index or destinationidentity to be used by the UE 124 in sidelink transmission, sidelinkquality of service information to be used by the UE 124 in sidelinktransmission, frequency information list to be used by the UE 124 insidelink transmission, or sidelink transmission/cast type to be used bythe UE 124 in sidelink transmission.

Then, the UE 124 may receive a RRC message from the WANN 118. The RRCmessage may indicate whether the UE 124 is allowed to obtain sidelinkresource allocation via the UE 102.

Optionally, the RRC message may include, for example, information ontransmission resource pool, which indicates the range of transmissionresource pool of the UE 124. The RRC message may further include, forexample,

-   -   a transmission type indicating that the UE 102 is capable of        assisting in allocating sidelink resources for sidelink        transmission of the user equipment in the transmission type;    -   a destination identity indicating that the UE 102 is capable of        assisting in allocating sidelink resources for sidelink        transmission of the UE 124 with the destination identity;    -   a sidelink quality of service information indicating that the UE        102 is capable of assisting in allocating sidelink resources for        sidelink transmission of the UE 124 with the sidelink quality of        service information; and    -   a range of HARQ process id list indicating that the UE 102 is        capable of assisting in allocating sidelink resources for        sidelink transmission of the UE 124 with a HARQ process id        within the range of HARQ process id list.

Optionally, prior to transmitting, to the UE 124, the response messageindicating whether to assist in allocating sidelink resources for the UE124 (210), the UE 102 may transmit an RRC message to the WANN 118 torequest for the authorization to assist in allocating sidelink resourcefor the UE 124. The RRC message may include, for example, one or moreidentification information of the UE 124, power saving information ofthe UE 124; sidelink destination index or destination identity in whichthe UE 124 is interested, in sidelink transmission; sidelink quality ofservice information to be used by the UE 124 in sidelink transmission;frequency information list in which the UE 124 is interested, insidelink transmission; and sidelink transmission/cast type to be used bythe UE 124 in sidelink transmission.

Then, the UE 102 may receive, from the WANN 118, an RRC messageindicating whether to authorize or allow the UE 102 to assist inallocating sidelink resources for the UE 124. The RRC message mayfurther include, for example,

-   -   an identification information of user equipments indicating that        the UE 102 could assist in allocating sidelink resources for the        user equipments,    -   information on a transmission resource pool indicating that the        UE 102 assists to allocate sidelink resources in the        transmission resource pool,    -   scheduling request configuration set information to configure        scheduling request resources for the UE 124,    -   a range of Hybrid Automatic Repeat Request (HARQ) process id        list indicating that the UE 102 is capable of assisting in        allocating sidelink resources for sidelink transmission of the        UE 124 with a HARQ process id within the range of HARQ process        id list.    -   destination identity indicating that the UE 102 is capable of        assisting in allocating sidelink resources for sidelink        transmission of the UE 124 with the destination identity,    -   a quality of service information indicating that the UE 102 is        capable of assisting in allocating sidelink resources for        sidelink transmission of the UE 124 with the quality of service        information,    -   a transmission type indicating that the UE 102 is capable of        assisting in allocating sidelink resources for sidelink        transmission of the UE 124 in the transmission type, and    -   a list of sidelink radio bearers (SLRB) or logic channels        indicating that the UE 102 is capable of assisting in allocating        sidelink resources for the sidelink radio bearers or logic        channels of the UE 124.

In some other implementations, the UE 124 may support multiple mode ofsidelink resource allocation. For example, the UE 124 may receive asidelink configuration message indicating a plurality of modes ofsidelink resource allocation that can be simultaneously used by the UE124. The UE 124 may then determine a set of modes of sidelink resourceallocation among the plurality of sidelink resource allocation; and usethe set of modes of sidelink resource allocation simultaneously toobtain sidelink resource allocation for sidelink communication. Theplurality of modes of sidelink resource allocation may include two ormore of a mode for resource allocation by a serving cell, a mode forresource allocation by UE autonomous resource selection, or a mode forresource allocation via assistance from a second UE. Optionally, the UE124 may further receive an indication information for indicating PC5RATs and simultaneous modes of sidelink resource allocation supported byeach of the PC5 RATs or a cross RAT indication information forindicating simultaneous modes of sidelink resource allocation supportedby cross RAT. Optionally, the UE 124 may further receive a priorityinformation indicating a relative priority among the plurality of modesof sidelink resource allocation.

Second Embodiment (Determining Candidate Anchor UEs and Selecting anAnchor UE from the Candidate Anchor UEs)

By way of examples, this embodiment describes the manners in which theUE 124 selects a specific user equipment such as the UE 102 to assist inallocating sidelink resources for the UE 124 when multiple userequipments are available to serve as an anchoring user equipment toassist in allocating sidelink resources for the UE 124. Once the UE 124selects a particular UE to serve as its anchor user equipment, theexample sidelink resource allocation assistance procedure described inthe first embodiment above applies.

The UE 124 may receive sidelink messages from a plurality of userequipments such as the UEs 102 and 126. The sidelink messages mayindicate that the user equipments sending the sidelink messages canserve as anchor user equipments and may include information indicatingqualification to serve as anchor user equipments. Such a sidelinkmessage may include the various information discussed above in relationto 202 of FIG. 2 as applied to UE 102 or UE 126. Additionally oroptionally, such a sidelink message may include an indication whetherthe user equipment sending the sidelink message is a group header ofsidelink communication group. Then, based on the sidelink messages, theUE 124 may identify which one of the plurality of user equipments is agroup header of a sidelink communication group of which the UE 124 is amember. If such user equipment is identified, the UE 124 may directlyselect that head user equipment to assist in allocating sidelinkresources for the UE 124.

Alternatively or additionally, the UE 124 may first select candidateuser equipments meeting a predetermined candidate condition from theplurality of user equipments based on the sidelink messages. Thepredetermined candidate condition may include, for example, at least oneof the following items:

-   -   loading rate of a candidate user equipment being lower than a        loading rate threshold,    -   a number of user equipments which a candidate user equipment is        assisting in allocating sidelink resources is lower than a        number threshold,    -   channel quality of a candidate user equipment is higher than a        channel quality threshold,    -   a range of quality of services supported by a candidate user        equipment includes a quality of service of a sidelink data that        the UE 124 is to transmit,    -   resource available for allocation by a candidate user equipment        is more than a resource availability threshold,    -   resource usage rate of resources to be allocated by a candidate        user equipment is lower than a resource usage rate threshold,    -   a CBR of a transmission resource pool of a candidate user        equipment is lower than a CBR threshold,    -   a list of sidelink group communication destination identifiers        includes a sidelink group communication destination identifier        of sidelink data that the UE 124 is to transmit,    -   a candidate user equipment and the UE 124 belong to a same        sidelink communication group,    -   a geographical distance between a candidate user equipment and        the UE 124 is less than a geographical distance threshold, or    -   a candidate user equipment and the UE 124 are being served in a        same cell.

Then, the UE 124 may select one of the candidate user equipmentssatisfying one or more of the conditions above to assist in allocatingsidelink resources for the UE 124. The selection from the candidate userequipments may be based on the selected candidate user equipment meetinga predetermined selection condition, which may include, for example oneof the following conditions:

-   -   the candidate user equipment is a group header of a sidelink        communication group.    -   the candidate user equipment has a best channel quality between        the candidate user equipment and a cell serving the candidate        user equipment or between the candidate user equipment and the        UE 124,    -   the candidate user equipment and the UE 124 belong to a same        sidelink communication group,    -   the candidate user equipment and the UE 124 are being served in        a same cell,    -   a resource allocation mode of the candidate user equipment is        wireless access network node scheduling mode,    -   the candidate user equipment has a most resources available to        be allocated, the candidate user equipment has a lowest resource        usage rate with respect to resources to be allocated by the        candidate user equipment,    -   a transmission resource pool of the candidate user equipment has        a lowest channel busy ratio,    -   the candidate user equipment supports a road side unit function,        or    -   the candidate user equipment supports a relay function.

Optionally, before selecting the candidate user equipments meetingpredetermined criteria from the plurality of user equipments, the UE 124may receive the predetermined criteria from the WANN 118. For example,the UE 124 may receive, from the WANN 118, the metric values such as theloading rate threshold, the number threshold, the channel qualitythreshold, a range of quality of services supported by the userequipment, and the geographical distance threshold. Alternatively, themetric values may be pre-configured in the UE 124.

Third Embodiment (Releasing an Anchor UE from Assisting in SidelinkResource Allocation)

The UE 124 of FIG. 1 may select, for example, the UE 102 as the anchorUE and obtain assistance in sidelink resource allocation from the UE 102following the various procedures described above in the first embodimentand the second embodiment. The connection between the UE 124 and the UE102, for example, may be implemented as a unicast connection (eventhough connections of other cast types may be feasible). When such aconnection is released and thus UE 124 and UE 102 is effectivelydisconnected, the responsibility of UE 102 as being the anchor UE forthe UE 124 may be correspondingly released. In other words, after theconnection between the UE 124 and the UE 102 is released, the UE 102would no longer act as the anchor UE for assisting the UE 124 insidelink resource allocation.

For example, such a connection between the UE 124 and the anchor UE 102may time out (e.g., a T400 timeout) or a sidelink RRC reconfigurationmay fail, e.g., as indicated by a sidelink radio link control (RLC)entity that a maximum number of retransmissions for a specificdestination has been reached. In either of these and some othersituations, the connection between the UE 102 and the UE 124 may beconsidered as being released. Then the UE 102 is no longer considered asthe anchor UE for assisting the UE 124 in sidelink resource allocation.

However, in some situations, there may be no data transmission betweenthe anchor UE 102 and the UE 124 for a long period of time. Theconnection between the UE 124 and the UE 102 may have lost alreadyduring that period of time (e.g., because the distance between the UE124 and UE 102 has grown to be too large), yet such disconnection may beundetected because there has been no data transmission and thus nodetectable T400 timeout and no detectable RRC reconfiguration failure.In such situations, the UE 102 may still be considered as the anchor UEfor the UE 124 even though the connection between the UE 102 and the UE124 has been lost. Therefore, to provide more efficient resourceallocation, it may be desirable to have a separate mechanism forreleasing the UE 102 from being the anchor UE for the UE 124.

In some implementations, a timer may be used to provide a separatemechanism for releasing the UE 102 from acting as the anchor UE for theUE 124. Such a timer may be referred to as a release timer. The releasetimer may be configured, activated (restarted) and deactivated (stopped)according to logic flow 300 of FIG. 3 . For example, as shown, by 310,the release timer may be initially configured with a predefine timeparameter. Such time parameter may be obtained from a serving cell ofeither the UE 124 or the anchor UE 102. Alternatively the initial timeparameter may be pre-configured in the UE 124 or UE 102. As shown in320, the release timer may be conditionally restarted (e.g., to countdown from the initial value) at various stage. For example, the releasetimer may be restarted when or after the UE 124 transmits a sidelinkscheduling request (SR) or buffer status report (BSR) to the UE 102,e.g., at 220 of FIG. 2 . Alternatively, the timer may be restarted whenthe UE 124 transmits a sidelink information or sidelink UE assistantinformation included in, for example, the sidelink request message 206of FIG. 2 . As further shown by 330, the activated release timer may beconditionally deactivated (e.g., stopped from counting down). Forexample, the release timer may be deactivated (stopped) when the UE 124receives sidelink resource allocation from the anchor UE 102.

The release timer may be monitored as it counts down. The release of theUE 102 from being the anchor UE for the UE 124 may then be triggeredwhen the timer expires. Such a trigger due to the timer expiry may beimplemented in parallel to other release mechanisms or triggers. Theseother release triggers, for example, my include but are not limited to

-   -   when the UE 124 enters an RRC sidelink connection state,    -   when the UE 124 receives a configuration information from its        serving cell indicating that the first UE is to transmit        sidelink communication based on network scheduling, that the        first UE is to transmit sidelink communication based on        autonomous resource selection of the first UE,    -   when the UE 124 a configuration information from its serving        cell indicating that it is no longer allowed to use other UEs to        assist in allocating sidelink resources,    -   when the UE 102 is no longer qualify to service as an anchor UE        for assisting other UEs in sidelink resource allocation,    -   when the serving cell of the UE 102 indicates to the UE 102 that        it cannot serve as an anchor UE for assisting other UEs in        sidelink resource allocation,

When any of the conditions above is triggered or the timer expires, theUE 102 may be released from acting as the anchor in assisting the UE 124in sidelink resource allocation. The release procedure, as describedbelow in several examples, may be initiated by the UE 124 or the UE 102.In general, a release message may be sent from one UE to the other UE.The release message may further include an indication of the cause forthe release. The cause may include time expiration or any one of thetriggering conditions above. The other UE receiving the release messagemay send a response message.

Once the UE 102 is released from acting as the anchor UE for the UE 124,various options may be provided as to the sidelink resources alreadyallocated to the UE 124 by the UE 102. For example, UE 124 may not beallowed to continue using the sidelink resources previously allocated bythe released UE 102. For another example, and to promote sidelinkservice continuity, the UE 124 may be allowed to continue using thesidelink resources previously allocated by the UE 102 even if the UE 102has been released from the anchor role. Alternatively, the UE 124 may beallowed to use resources from some emergency or exceptional sidelinkresource pool in place of the sidelink resource previously allocated bythe released UE 124. Correspondingly, the release message or some othermessage to the UE 124 may include an indicator for indicating whether ornot the UE 124 can continue to use the sidelink resources previouslyallocated by the released UE 102.

In some implementations, the UE 124 may initiate a release of UE 102from acting as the anchor UE for the UE 124. An example is shown in thelogic flow 400 of FIG. 4 . In 410, the UE 124 determines an indicationthat one or more release conditions have been triggered and that the UE102 is not to continue acting as the anchor UE in assisting the UE 124in sidelink resource allocation. The release conditions may include atleast one of:

-   -   the release timer has expired,    -   the UE 124 has entered an RRC sidelink connection state,    -   the UE 124 receives a configuration information from its serving        sell indicating that the sidelink resources for the UE 124 is to        transmit sidelink communication based on network scheduling by,        e.g., its serving sell,    -   the UE 124 receives a configuration from its serving cell        indicating that it is to transmit sidelink communication based        on autonomous resource selection of the UE 124,    -   the UE 124 receives a configuration information from its serving        sell indicating that it is no longer allowed to use other UEs to        assist in allocating sidelink resources or its sidelink resource        allocation is not to be provided by other UEs,    -   a number of transmission reaches a maximum number of        retransmission at the UE 124,    -   the UE 124 satisfying at least one of a set of wireless        communication environmental conditions.

The initial time value of the release timer and the maximum number ofretransmission may be configured in the UE 124 by its serving cell ormay be configured by the UE 102. The release timer may be restarted orthe number of retransmission may be incremented by one by the UE 124when a side scheduling request or a sidelink buffer status report istransmitted by the UE 124, or when a sidelink UE information or asidelink UE assistant information is transmitted by the UE 124. Therelease timer may be stopped or the number of transmission may be set tozero when the UE 124 receives a sidelink resource allocation informationfrom the UE 102.

The set of wireless communication environmental conditions above mayinclude but are not limited:

-   -   the UE 124 enters a cellular coverage (when it not previously        covered by a cell),    -   a channel quality between the UE 124 and the UE 102 is less than        a first channel quality threshold value,    -   a distance between the UE 124 and the UE 102 larger than a        second distance threshold value,    -   the UE 124 detects that the CBR of the allocable sidelink        resource pool is lower than a third CBR threshold value,    -   the UE 124 leaves a sidelink communication group to which the UE        102 belongs,    -   the UE 124 identifies another UE more suitable for acting as the        anchor UE to assist the UE 124 in sidelink resource allocation        (more details are provided below in relation to the fifth        embodiment).

As shown in 420 of FIG. 4 , once the one or more release condition istriggered in 410 of FIG. 4 , the UE 124 sends a release message to theUE 102. The release message is used to indicate to the UE 102 that theUE 102 is released and is no longer responsible for acting as the anchorUE for assisting the UE 124 in sidelink resource allocation. Dependingon the cause of the release (determined by the various triggers above),the release message may be used to alternatively to indicate to the UE102 that a mode for sidelink resource allocation mode for UE 124 haschanged (e.g., from UE assisted to allocation by a serving cell).

The release message may optionally include an indication of cause(s) ofthe release. In correspondence with the release triggers above, therelease cause(s) may include one or more of:

-   -   release timer expiry,    -   a change of a RRC connection status;    -   a change of a mode of sidelink resource allocation;    -   a first channel quality degradation between the first UE and its        serving cell;    -   a second channel quality degradation between the first UE and        the second UE;    -   a low channel busy ratio (CBR) of configured sidelink resources        pool is detected;    -   leaving a sidelink communication group including the second UE;        or    -   a determination by the first UE to switch to a third UE as the        anchor UE to assist the first UE in the sidelink resource        allocation. Optionally, the release message may include an        indicator for indicating whether or not the UE 124 is to        continue to use the sidelink resources previously allocated by        the released anchor UE 102.

Optionally, the release procedure 400 may further include step 430 ofFIG. 4 , in which the anchor UE 102 receives the release message andtransmit a response to the UE 124 to acknowledge the release of the UE102 from acting as the anchor UE for assisting the UE 124 in sidelinkresource allocation.

In some implementations, the release procedure 400 may further includestep 402 prior to the step 410 where the release condition is determinedby the UE 124. In particular, in step 402, the UE 124 may first obtainthe various threshold values described above for triggering the release,including but not limited to the first channel quality threshold value,the second distance threshold value, and the third CBR threshold valueThese threshold values may be obtained by the UE 124 from its servingcell. Alternatively, these threshold values may be pre-configured in theUE 124.

In some other example implementations, the anchor UE 102 rather than theUE 124 may initiate the release of UE 102 from acting as the anchor UEfor the UE 124. An example is shown in the logic file 500 of FIG. 5 . In510, the UE 102 determines that it is no longer responsible forassisting the UE 124 in sidelink allocation. The UE 102 may decide torelease itself from acting as an anchor UE for the UE 124 under variousexample conditions. For example, a serving cell of the UE 102 may send aconfiguration message to the UE 102 to indicate to the UE 102 that theUE 124 is to obtain sidelink resource allocation by choose resources byitself (or that UEs are to transmit sidelink communication based onautonomous resource selection). For another example, the serving cell ofthe UE 102 may send a configuration message to the UE 102 to indicate tothe UE 102 is no longer permitted to assist other UEs in sidelinkresource allocation. For yet another example, the UE 102 may determineone or more other release triggers are satisfied. These release triggersmay include but are not limited to:

-   -   a channel quality between UE 102 and its serving cell is less        than a first channel quality threshold value,    -   a current load rate of UE 102 is higher than a second load rate        threshold value;    -   the UE 102 detects that a CBR of allocable sidelink resource        pool is above a third CBR threshold value;    -   the channel quality between the UE 102 and the UE 124 is less        than a fourth channel quality threshold value,    -   a distance between the UE 102 and the UE 124 is greater than a        fifth distance threshold value,    -   the UE 102 leaves a sidelink communication group to which the UE        124 belongs,    -   the UE 102 cease to be a head UE of a sidelink communication        group to which the UE 124 belongs.

As shown in FIG. 5 , the release procedure 500 further include step 520,in which the anchor UE 102 sends a release message to the UE 124. Therelease message may be used to indicate to the UE 124 that the UE 102 isno longer to service as the anchor UE in assisting the UE 124 insidelink resource allocation. In correspondence to the triggers leadingto the release, the release message may include one of more causes forthe release. The causes may include but are limited to:

-   -   channel quality deterioration,    -   change of an RRC connection status,    -   changes in mode of resource acquisition,    -   UE 102 leaving the sidelink communication group,    -   UE 102 ceasing to act as head UE of the sidelink communication        group,    -   high current load rate,    -   high CBR,    -   large distance between the UE 102 and UE 124,

The channel deterioration cause above may include either deteriorationof the channel quality between the UE 102 and its serving cell or thechannel quality between the UE 102 and the UE 124.

As further shown in FIG. 5 , the release procedure 500 may furtherinclude step 530 in which the UE 124 receives the release message fromthe UE 102 and respond to acknowledge the release of the UE 102 fromacting as the anchor UE in assisting the UE 124 in sidelink resourceallocation.

Optionally, the release message transmitted by the UE 102 may include anindicator for indicating to the UE 124 whether or not the UE 124 cancontinue to use the sidelink resources previously allocated by thereleased anchor UE 102.

In some implementations, the release procedure 500 may further includestep 502 prior the step 510 where the release condition is determined bythe UE 102. In particular, in step 502, the UE 124 may first obtain thevarious threshold values described above for triggering the release,including but not limited to the first channel quality threshold value,the second load rate threshold value, the third CBR threshold value, thefourth channel quality threshold value, the fifth distance thresholdvalue. These threshold values may be obtained by the UE 102 from itsserving cell. Alternatively, these threshold values may bepre-configured in the UE 102.

Fourth Embodiment (Selecting Head UE as the Anchor UE)

In some implementations, the UE 102 and the UE 124 may belong to a samesidelink group-cast group. The UE 102 may particular be configured asthe head UE of the group-cast group. When the UE 102 needs assistance insidelink allocation, it may select the head UE as the anchor UE. Forexample, the UE 124 may first identify the head UE among the group viasignaling exchange with its serving cell and/or other UEs in thesidelink group-cast group. It may then request and establish the head UE102 to serve as the anchor UE in assisting it in sidelink resourceallocation. When either of the UE 102 or UE 124 (as the head UE and theanchor UE) leaves the sidelink group-cast group, the UE 124 may bereleased from acting as the anchor UE for the UE 102 either at theinitiation of the UE 124 or at the initiation of the UE 102, asdescribed above in the third embodiment.

Fifth Embodiment (Switching to Anchor UE)

For the UE 124 being currently assisted by the anchor UE 102 in sidelinkresource allocation, and when the UE 102 has not been release fromacting as the anchor UE, one or more other UEs may have become morequalified as acting as an anchor UE for the UE 102. The anchor UE forthe UE 124 may be switched to one of the more qualified UEs. In someimplementations, the UE 124 may send a scheduling request to a morequalified UE to request it to service as the anchor UE. After anacceptance and confirmation by the more qualified UE, the originalassisting relationship between the UE 102 and the UE 124 may be releasedand the more qualified UE would replace the UE 102 as the anchor UE forassisting the UE 102 in sidelink resource allocation.

In some implementations, to avoid frequent switching of anchor UE and aresulting reduction in system efficiency, it may be required that acandidate anchor UE for the UE 124 to switch to be more qualified as ananchor UE than the UE 102 by at least a threshold improvement in atleast some aspects, such as a channel quality with its serving cell, achannel quality with the UE 124, a load rate, a distance to the UE 124,and the like, as described in more detail below.

FIG. 6 shows an example logic flow 600 for switching anchor UE. In step610, the UE being assisted in sidelink resource allocation, the UE 124,selects a UE other than the UE 102 as its anchor UE. In step 520, theassisted UE may initiate a release procedure to release the UE 102 fromacting as the anchor UE in assisting the UE 124 in sidelink resourceallocation by sending a release message to the UE 102. The releasemessage is used to indicate to the UE 102 that it is no longerresponsible for acting as the anchor UE for assisting the UE 124 insidelink resource allocation. Example content of the release message andthe release procedure thereafter may follow the description above in thethird embodiment. In particular, the release message may include anindicator for indicating whether or not the sidelink resource previouslyallocated by the UE 102 is to be continued used for sidelinkcommunication by the UE 124.

As further shown in 620 of FIG. 6 , the current anchor UE 102 isreleased from its anchor role for the UE 124. The in 630, the assistingrelationship between the newly selected UE and the UE 124 may beestablished and the newly selected UE may then act as the anchor UE forthe UE 124. The procedure for establishing the newly selected UE as theanchor UE may follow the procedure described in the various embodimentsabove. The step 630 may be alternatively performed before step 620.

The criteria for the UE 124 in selecting the new anchor UE, ordetermining that the newly selected UE is more qualified than the UE 102by at least some threshold may include at least one of:

-   -   a difference between a load rate of the UE 102 and a load rate        of the new UE is greater than a first load rate difference        threshold value,    -   a difference between a CBR of configured resource pool of the UE        102 and a CBR of configured resource pool of the new UE is        greater than a second CBR difference threshold value,    -   a difference between a channel quality between the new UE and        the UE 124 and a channel quality between the UE 102 and the UE        124 is greater than a third channel quality difference threshold        value,    -   a difference between a channel quality between the new UE and        its serving cell and a channel quality between the UE 102 and        the serving cell of the UE 102 is greater than a fourth channel        quality difference threshold value,    -   a difference between a distance between the UE 102 and the UE        124 and a distance between the new UE and the UE 124 is greater        than a fifth distance difference threshold value.

Optionally, the various difference threshold above may be obtained bythe UE 124 from its serving cell or may be pre-configured in the UE 124,as shown in 602 of FIG. 6 .

Sixth Embodiment (Sidelink Resource Allocation by an Anchor UE WhenAssisting More Than One UEs)

In some implementations, one UE can serve as anchor UE for multipleother UEs. For example, the UE 102 of FIG. 1 may assist both UE 124 andUE 126 in sidelink resource allocation. In some situations, the UE 102may allocate the sidelink resources to UE 124 and UE 126 in theaggregate. The UE 124 and UE 126 may then select from the allocatedsidelink resources for sidelink transmission. For example, UE 124 and UE126 may be allowed to randomly select from the allocated resources. Assuch, resource selection collision may occur between UE 124 and UE 126.To avoid resource selection collision, the UE 124 and the UE 126 mayperforming sensing of the resources prior to making any selection.

In some other implementations, the UE 102 may act as anchor UE for boththe UE 124 and the UE 126 and may allocate separate resources for the UE124 and the UE 126. As such, the UE 124 and the UE 126 may each selectfrom the allocated resources, e.g., randomly, without having toperforming sensing to avoid resource selection collision. However,because the UE 102 may not be aware of the resource need for the UE 124and the UE 126, such separate allocation of sidelink resources for theUE 124 and the UE 126 may be sometimes either over-allocated orunder-allocated, leading to reduction of sidelink resource utilizationefficiency.

In yet some other implementations as described in more detail below, theUE 102 may allocate resources to a particular assisted UE such as the UE124. The allocation may include a sharing indicator to indicate to theUE 124 whether the resources included in the allocation are shared withany other UEs. The UE 124 may then determine whether or not to performresource sensing prior to selecting resources from the allocation. Forexample, if the sharing indicator indicates that the allocated resourcesare shared with other UEs, then the UE 124 may need to perform sensingprior to selection of resources from the allocation in order to avoidresource selection collision with the other UEs. However, if the sharingindicator indicates that the resource allocation is not shared withother UEs, then the UE 124 may perform random resource selection fromthe allocation without having to perform sensing.

Such implementations provide flexibility in using the anchor UE 102 toassist in resource allocation for multiple UEs. For example, the UE 102may use a mixed type of resource allocation. Specifically, the UE 102may allocate separate non-shared resources to some UEs (if, for example,the UE 102 can estimate or have other ways of knowing an approximateresource need for these UEs), while allocating shared resources to someother UEs. The UE 102 only needs to provide an allocation information toeach assisted UE with an indicator indicating whether or not theresources with the allocation for the particular UE are shared with anyother UEs. Such indication may be provided at a granularity of theallocation level, or a granularity of resource level. For example, theUE 102 may include a single indicator that is applicable to the entireresource allocation for a particular assisted UE. Alternatively, the UE102 may include multiple indicators in an allocation for a particularassisted UE to indicate whether different portions of the resourceswithin the allocation are shared with other UEs.

FIG. 7 shows an example logic flow 700 for allocating sidelink resourcesby the anchor UE 102 to the assisted UE 102 while also assisting otherUEs in sidelink resource allocation. In step 701, the UE 124 sends aresource allocation request message to the anchor UE 102. The allocationrequest message may be transmitted via a PC5 RRC interface or a PC5 MACCE interface, or a sidelink control information interface. Theallocation request message my include at least one of:

-   -   Resource allocation assistant information for the UE 124,    -   sidelink information for the UE 124,    -   BSR of the UE 124,    -   UE 124's resource allocation request.

The Resource allocation assistant information may include at least oneof:

-   -   a traffic periodicity,    -   a timing offset,    -   a message size,    -   a sidelink destination index,    -   a sidelink quality of service (QoS) flow identity.

The sidelink information may include at least one of:

-   -   an information list of interested frequency points,    -   a destination identity,    -   a transmission cast type,    -   a sidelink QoS information list comprising at least one of a QoS        flow identity or QoS profile index.

As shown in FIG. 7 in step 704, the UE 102 receives the allocationrequest message and generate resource allocation information. In step706, the UE 102 sends the resource allocation information to the UE 124.In step 708, the UE 124 receives the resource allocation information.The resource allocation information may include at least one of:

-   -   Usable/available sidelink resource allocation,    -   unusable/unavailable sidelink resource allocation,    -   a sharing indicator,    -   a mode for selection of the allocated resources by the first UE.

The sharing indicator above is included to indicate whether or not theavailable sidelink resources allocated by the UE 102 are shared with atleast one other UEs. If the available resources are shared, the UE 124needs to perform sensing before selecting sidelink resources from theavailable sidelink resources to reduce collision with other UEs assistedby the UE 102. If the available resources are indicated as not beingshared, the UE 124 may randomly select from the available resourceswithout performing sensing. Correspondingly, the mode for selectionincluded in the resource allocation information above may include one ofa sensing mode or a random selection mode.

As shown in 710 of FIG. 7 , the UE 124 may then determine whethersensing is required based on the sharing indicator and/or the selectionmode in the received resource allocation information from the UE 102. Atstep 712, the UE 124 perform selection of resources for sidelinktransmission, for example, either randomly or after sensing.

Optionally, before step 702, the UE 124 may first detect whether or notthe CBR of the sidelink resource pool is lower than a CBR threshold. TheUE 124 may obtain such CBR threshold from its serving cell or from theUE 102 or such CBR threshold may be pre-configured in the UE 124.

In some other implementations, the procedure 700 of FIG. 7 may befurther enhanced to include resource allocation limitation imposed by aserving cell. As such, some additional resource allocation informationmay be needed from the UE 124. Such additional resource information mayinclude but is not limited to a BSR of the UE 124, or other resourceallocation assistant information of the UE 124 described above. Forexample, the UE 124 may send its sidelink BSR to the anchor UE 102 forfurther limiting the sidelink resource allocation. If the current BSR isthe same as the original BSR, the UE 124 may need to send to the anchorUE 102 priority information for logic channels or a logic channel group,or the UE 102 may directly configure logic channels or logic channelgroup for the UE 124. For example, the UE 102 may configure a mappingbetween logic channel group and QoS levels. For another example, the UE124 may configure the logic channels or logic channel group and transmitthe priority information for such logic channels or logic channel groupto the UE 102.

A logic flow for such implementations is similar to the logic flow 700of FIG. 7 , with some additional steps before the step 702. For examplebefore step 702, the assisted UE 124 may first receive a configurationof logic channels or a logic channel group from the anchor UE 102. Sucha configuration indicates QoS information corresponding to each of thelogic channels or logic channel group. Alternatively, the UE 124 mayfirst communicate logic channel or logic channel group information tothe UE 124. The information indicates QoS information corresponding toeach of the logic channels or logic channel group. The QoS informationmay include but is not limited to one or more of, for example, priorityinformation, a resource type (GBR, delay critical GBR or Non-GBR), QoSflow identity (QFI), QoS control information (QCI), packet delayinformation, or reliability information.

Seventh Embodiment (Simplified Buffer Status Report)

In some alternative implementations of the sixth embodiment, the BSRinformation may be simplified. For example, the anchor UE 102 may onlyneed to report buffer size for each packet priority (PPPP) or buffersize per QoS list for assisting the UE 124 in sidelink resourceallocation. Further, if the anchor UE 102 needs to assist allocating allsidelink traffic resources for the assisted UE 124, it may also needinformation such as service destination index. The QoS list and theservice destination index above may need to be provided to the anchor UE102 prior to sidelink resource allocation.

As such, in step 702 of the logic flow 700 in FIG. 7 , the allocationrequest message sent from the UE 124 may include one or more priorityinformation and buffer sizes corresponding to the one or more priorityinformation. Additionally or alternatively, the allocation requestmessage may include one or more QoS information and buffer sizescorresponding to the one or more QoS information. Optionally, theallocation request message may further include service destinationindex. Correspondingly, before the step 702 of the logic flow 700 inFIG. 7 , the assisted UE 124 may send a list of QoS profiles of sidelinkQoS flows to the anchor UE 102. The QoS information above may includeone or more of QoS index for identifying specific QoS profiles in thelist of QoS profiles. An example list of QoS profiles is shown in List 1below and explained in Table 1 below.

List 1 sl-QoS-InfoList SEQUENCE (SIZE (1..maxNrofSL-QFIsPerDest)) OFSL-QoS-Info SL-QoS-Info ::=  SEQUENCE {   sl-QoS-FlowIdentity  SL-QoS-FlowIdentity,   sl-QoS-Profile   SL-QoS-Profile OPTIONAL }SL-QoS-Profile ::=  SEQUENCE {   sl-PQI  SL-PQI  OPTIONAL,   sl-GFBR INTEGER (0..4000000000)  OPTIONAL,   sl-MFBR   INTEGER (0..4000000000) OPTIONAL,   sl-Range  INTEGER (1..10000)  OPTIONAL,  ... } SL-PQI ::=  CHOICE {   sl-StandardizedPQI   INTEGER (1..83),  sl-Non-StandardizedPQI  SEQUENCE {   sl-ResourceType ENUMERATED {gbr,non-GBR, delayCriticalGBR, spare1} OPTIONAL,   sl-PriorityLevel INTEGER(0..7)  OPTIONAL,   sl-PacketDelayBudget INTEGER (0..1023)  OPTIONAL,  sl-PacketErrorRate  INTEGER (0..9)   OPTIONAL,   sl-AveragingWindow INTEGER (0..4095)   OPTIONAL,   sl-MaxDataBurstVolume  INTEGER(0..4095)   OPTIONAL,  ...  } }

TABLE 1 sl-QoS-InfoList Includes the QoS profile of the sidelink QoSflow. sl-QoS-FlowIdentity This identity uniquely identifies one sidelinkQoS flow between the UE and the network in the scope of UE, which isunique for different destination and cast type. SL-QoS-Profile fielddescriptions sl-GFBR Indicate the guaranteed bit rate for a GBR QoSflow. The unit is: Kbit/s sl-MFBR Indicate the maximum bit rate for aGBR QoS flow. The unit is: Kbit/s sl-PQI This filed indicates either thePQI for standardized PQI or non- standardized QoS parameters. sl-RangeThis field indicates the range parameter of the Qos flow. SL-PQI fielddescriptions sl-Averaging Window Indicates the Averaging Window for aQoS flow, and applies to GBR QoS flows only. Unit: ms. The default valueof the IE is 2000 ms. sl-MaxDataBurstVolume Indicates the Maximum DataBurst Volume for a QoS flow, and applies to delay critical GBR QoS flowsonly. Unit: byte. sl-PacketDelayBudget Indicates the Packet Delay Budgetfor a QoS flow. Upper bound value for the delay that a packet mayexperience expressed in unit of 0.5 ms. sl-PacketErrorRate Indicates thePacket Error Rate for a QoS flow. The packet error rate is expressed asScalar × 10−k where k is the Exponent. sl-PriorityLevel Indicates thePriority Level for a QoS flow. Values ordered in decreasing order ofpriority, i.e. with 1 as the highest priority and 127 as the lowestpriority. sl-StandardizedPQI Indicate the the PQI for standardized PQI.

Eighth Embodiment (Scheduling Request)

In some other alternative implementations to the sixth embodiment above,the BSR may not be included in the allocation request message of step702. The allocation request may only be made via scheduling request(SR). Different scheduling request configuration may correspond to thelevel of size of resource allocations. The anchor UE 102 may transmitone or more SR configuration information to the assisted UE 124. The oneor more SR configuration information may be used by the assisted UE 124in requesting sidelink resource allocation.

The SR configuration information may be requested by the anchor UE 102from its serving cell. For example, the serving cell may be configureswith a scheduling request list. The anchor UE 102 may determine a SRconfiguration information for a particular assisted UE such as the UE124.

As such, in these implementations, the resource allocation requestmessage of step 702 of FIG. 7 may include one or more SRs eachcorresponding to different priority information. Each SR carriesseparate buffer size information.

Correspondingly, before such a modified step 702, the assisted UE 124may first receive SR configuration information, including a list of SRconfigurations. The assisted UE 124 may select SR configurationinformation from the list of SR configurations for configuring theassisted UE 124.

Throughout the specification and claims, terms may have nuanced meaningssuggested or implied in context beyond an explicitly stated meaning.Likewise, the phrase “in one embodiment/implementation” as used hereindoes not necessarily refer to the same embodiment and the phrase “inanother embodiment/implementation” as used herein does not necessarilyrefer to a different embodiment. It is intended, for example, thatclaimed subject matter includes combinations of example embodiments inwhole or in part.

In general, terminology may be understood at least in part from usage incontext. For example, terms, such as “and”, “or”, or “and/or,” as usedherein may include a variety of meanings that may depend at least inpart on the context in which such terms are used. Typically, “or” ifused to associate a list, such as A, B or C, is intended to mean A, B,and C, here used in the inclusive sense, as well as A, B or C, here usedin the exclusive sense. In addition, the term “one or more” as usedherein, depending at least in part upon context, may be used to describeany feature, structure, or characteristic in a singular sense or may beused to describe combinations of features, structures or characteristicsin a plural sense. Similarly, terms, such as “a,” “an,” or “the,” may beunderstood to convey a singular usage or to convey a plural usage,depending at least in part upon context. In addition, the term “basedon” may be understood as not necessarily intended to convey an exclusiveset of factors and may, instead, allow for existence of additionalfactors not necessarily expressly described, again, depending at leastin part on context.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present solution should be or are includedin any single implementation thereof. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present solution. Thus,discussions of the features and advantages, and similar language,throughout the specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages and characteristics ofthe present solution may be combined in any suitable manner in one ormore embodiments. One of ordinary skill in the relevant art willrecognize, in light of the description herein, that the present solutioncan be practiced without one or more of the specific features oradvantages of a particular embodiment. In other instances, additionalfeatures and advantages may be recognized in certain embodiments thatmay not be present in all embodiments of the present solution.

The invention claimed is:
 1. A method for releasing resource allocationassistance in wireless sidelink communication by a first user equipment(UE), comprising: determining, after an association between the first UEand a second UE is established for the second UE to assist the first UEin sidelink resource allocation, a release indication indicating thatthe first UE no longer needs the second UE to assist in the sidelinkresource allocation; and transmitting, upon the determination of therelease indication, a release information to the second UE forindicating to the second UE that the first UE no longer need the secondUE to assist in the sidelink resource allocation or that a mode for thesidelink resource allocation for the first UE has changed.
 2. The methodof claim 1, wherein the release indication is determined based on arelease condition comprising at least one of: expiry of a timerestablished by the first UE; entering into a radio resource control(RRC) connected states by the first UE; receiving a configuration by thefirst UE from its serving cell indicating that the first UE is totransmit sidelink communication based on network scheduling, that thefirst UE is to transmit sidelink communication based on autonomousresource selection of the first UE, or that the sidelink resourceallocation is not to be provided by other UEs; a number of transmissionsreaching a maximum number of transmissions at the first UE; or asidelink communication environment of the first UE satisfying apredetermined level.
 3. The method of claim 2, wherein an initial timevalue of the timer or the maximum number of transmissions is configuredin the first UE by its serving cell or is pre-configured or isconfigured by the second UE.
 4. The method of claim 3, wherein the timeris restarted or the number of transmissions is incremented by one by thefirst UE when: a sidelink scheduling request or a sidelink buffer statusreport is transmitted by the first UE; or when a sidelink UE informationor a sidelink UE assistant information is transmitted by the first UE.5. The method of claim 4, wherein the timer is stopped or the number oftransmissions is set at zero when the first UE receives a sidelinkresource allocation information from the second UE.
 6. The method ofclaim 4, further comprising: releasing, by the first UE, the associationbetween the first UE and the second UE; or releasing, by the first UE,the second UE as an anchor UE for the first UE in the sidelink resourceallocation.
 7. The method of claim 2, wherein a sidelink communicationenvironment of the first UE satisfying a predetermined level comprisesat least one of: entering a cellular coverage by the first UE; a channelquality between the first UE and the second UE being below a firstchannel quality threshold value; a distance between the first UE and thesecond UE being larger than a second distance threshold value; a channelbusy ratio (CBR) of configured sidelink resources pool as being lowerthan a third CBR threshold value; the first UE leaving a sidelinkcommunication group including the second UE; or determination by thefirst UE that a third UE is more suitable to serve as an anchor UE forthe first UE for the sidelink resource allocation.
 8. The method ofclaim 7, further comprising, prior to determining the releaseindication: obtaining, by the first UE from its serving cell, the firstchannel quality threshold value, the second distance threshold value, orthe third CBR threshold value; or determining, by the first UE viapre-configuration, the first channel quality threshold value, the seconddistance threshold value, or the third CBR threshold value.
 9. Themethod of claim 1, wherein the release information comprises a cause forrelease of the association between the first UE and the second UEcomprising at least one of: expiry of a timer; a change of an RRCconnection status; a change of a mode of sidelink resource allocation; afirst channel quality degradation between the first UE and its servingcell; a second channel quality degradation between the first UE and thesecond UE; a lower channel busy ratio (CBR) of configured sidelinkresources pool is detected; leaving a sidelink communication groupincluding the second UE; or a determination by the first UE to switch toa third UE as an anchor UE to assist the first UE in the sidelinkresource allocation.
 10. The method of claim 1, wherein the releaseinformation further indicates whether or not a sidelink resource alreadyallocated to the first UE by the second UE is to be continually used bythe first UE for a sidelink communication after the second UE isreleased as an anchor UE for the first UE.
 11. The method of claim 1,further comprising receiving by the first UE a response informationtransmitted by the second UE after the second UE receives the releaseinformation from the first UE.
 12. The method of claim 1, whereindetermining the release indication comprises identifying a third UE moresuitable as an anchor UE for assisting the first UE in sidelink resourceallocation.
 13. The method of claim 12, wherein identifying the third UEcomprises determining that the third UE is more suitable as the anchorUE for assisting the first UE in the sidelink resource allocation thanthe second UE by determining at least one of: a difference between aload rate of the first UE and a load rate of the third UE is greaterthan a first load rate difference threshold value; a difference betweena CBR of configured resource pool of the first UE and a CBR ofconfigured resource pool of the third UE is greater than a second CBRdifference threshold value; a difference between a channel qualitybetween the third UE and the first UE and a channel quality between thesecond UE and the first UE is greater than a third channel qualitydifference threshold value; a difference between a channel qualitybetween the third UE and its serving cell and a channel quality betweenthe second UE and the serving cell of the second UE is greater than afourth channel quality difference threshold value; or a differencebetween a distance between the second UE and the first UE and a distancebetween the third UE and the first UE is greater than a fifth distancedifference threshold value.
 14. The method of claim 13, wherein thefirst UE obtains the first load rate difference threshold value; thesecond CBR difference threshold value; the third channel qualitydifference threshold value; fourth channel quality difference thresholdvalue, and the fifth distance difference threshold value from itsserving sell or via pre-configuration.
 15. The method of claim 12, themethod further comprising, prior to transmitting the release informationto the second UE: transmitting a sidelink resource allocation assistancerequest to the third UE; and receiving an acknowledgement from the thirdUE indicating that the third UE agrees to act as the anchor UE to assistthe first UE in the sidelink resource allocation.
 16. A method forwireless sidelink resource allocation for a first UE, comprising:receiving, by the first UE, a sidelink configuration message indicatinga plurality of modes of sidelink resource allocation that can besimultaneously used by the first UE; and obtaining a sidelink resourceallocation, by the first UE, via two or more of the plurality of modesof sidelink resource allocation, wherein the plurality of modes ofsidelink resource allocation comprise two or more of a mode for resourceallocation by a serving cell, a mode for resource allocation by UEautonomous resource selection, or a mode for resource allocation viaassistance from a second UE.
 17. The method of claim 16, furthercomprising receiving, by the first UE: an indication information forindicating PC5 RATs and simultaneous modes of sidelink resourceallocation supported by each of the PC5 RATs; or a cross RAT indicationinformation for indicating simultaneous modes of sidelink resourceallocation supported by cross RAT.
 18. The method of claim 16, furthercomprising receiving, by the first UE a priority information indicatinga relative priority among the plurality of modes of sidelink resourceallocation.
 19. A first UE comprising a processor and a memory, whereinthe processor is configured to read computer code from the memory tocause the first UE to: receive a sidelink configuration messageindicating a plurality of modes of sidelink resource allocation that canbe simultaneously used by the first UE; and obtain a sidelink resourceallocation, via two or more of the plurality of modes of sidelinkresource allocation, wherein the plurality of modes of sidelink resourceallocation comprise two or more of a mode for resource allocation by aserving cell, a mode for resource allocation by UE autonomous resourceselection, or a mode for resource allocation via assistance from asecond UE.
 20. The first UE of claim 19, wherein the processor isfurther configured to execute the computer code to cause the first UE toreceive: an indication information for indicating PC5 RATs andsimultaneous modes of sidelink resource allocation supported by each ofthe PC5 RATs; or a cross RAT indication information for indicatingsimultaneous modes of sidelink resource allocation supported by crossRAT.